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PI Synchronous interface type is responsible for testing synchronous scenarios. In such cases, test validation is based on a receiver system response message and optionally on the documents created in S/4HANASAP Backend.
Please note that the receiver system will not be virtualized. The connnection connection must be working and the test validation will be performed based on the response from the receiver (after mapping in SAP PI/PO).
The optional validation of the SAP Backend document looks exactly the same as test type PI GUID Inbound.